Converging-diverging nozzle construction



June 27, 1961 w. E. HOWALD 2,989,845

CONVERGING-DIVERGING NOZZLE CONSTRUCTION Filed Dec. 2, 1957 4 Sheets-Sheet 1 INVENTOR. WERNER E..HIJWALD ATTEIR'NEY June 27, 1961 w. E. HOWALD 2,989,845

CONVERGING-DIVERGING NOZZLE CONSTRUCTION Filed D60. 2, 1957 4 Sheets-Sheet 2 INVENTOR. WERNER E.HDWALD BYZgZDL-BWKA- ATTORNEY June 27, 1961 w. E. HOWALD CONVERGING-DIVERGING NOZZLE CONSTRUCTION 4 Sheets-Sheet 3 Filed Dec. 2, 1957 IVENTOR. WERNER E. HDWALD A $2 ATT EIR'NEY June 27, 1961 w. E. HOWALD CONVERGING-DIVERGING NOZZLE CONSTRUCTION 4 Sheets-Sheet 4 Filed Dec. 2, 1957 I D I L E E m H IE fi Rm v E Na 3. mm m a N: I N: 1 m N N: 3 N: E N! K E Na vs 3 m2 3 E N: m V @W 2 NE 3. w". M Q\\ ON\ WM Q2 MW NN- flQ\ m Q Di aw Q:

fin 3V2 ATTDRNEY United States Patent 6 2,989,845 CONVERGING-DIVERGING NOZZLE CONSTRUCTION Werner-F. Howald, Ridgewood, NJ., assignor to Curtiss- Wright Corporation, a corporation of Delaware Filed Dec. 2, 1957, Ser. No. 699,953 2 Claims. (Cl. 60-356) This invention relates to exhaust nozzles and is particularly directed to a variable area exhaust nozzle for jet engines.

The exhaust nozzle of a jet engine may be provided with a shroud which is movable with the nozzle to minimize the engine drag. An object of the present invention comprises the provision of a novel nozzle actuating mechanism disposed between the nozzle and its shroud without materially restricting simultaneous adjustment of the nozzle shroud to a minimum drag position for each nozzle position. A further object of the invention comprises the utilization of turnbuckle-like devices connected together in end-to-end relation to form a novel annular structure about the nozzle which can be expanded or contracted to adjust the nozzle area.

A still further object of the invention comprises the provision of a nozzle made up of a plurality of movable nozzle segments arranged in a circumferential assembly and each having a novel construction for providing a film of a cooling medium over the inner surface of the nozzle and at the same time permitting easy replacement of portions of each nozzle segment.

Other objects of the invention will become apparent upon reading the annexed detailed description in connection with the drawing in which:

FIG. 1 is a diagrammatic view of an exhaust nozzle embodying the invention and showing the nozzle in a position of minimum throat and exit areas;

FIG. 2 is a view similar to FIG. 1 but showing the nozzle in a position of intermediate throat area and max? imum exit area;

FIG. 3 is a view similar to FIG. 1 but showing the nozzle in a position of maximum throat and exit areas;

FIG. 4 is a partial perspective view illustrating a portion of the nozzle actuating mechanism;

FIG. 5 is an enlarged longitudinal view of a portion of FIG. 1 partly in section and illustrating in elevation one nozzle member, its associated shroud member and its actuating mechanism;

FIGS. 6, 7, 8, 9 and are sectional views taken along lines 6-6, 77, 88, 99 and 10-10 of FIG. 5;

FIG. 11 is a sectional view taken along line 1111 of FIG. 6;

FIG. 12 is a sectional view taken along line 12-12 of FIG. 5 and particularly illustrating the turnbuckle devices of the nozzle actuating mechanism;

FIG. 13 is a view similar to FIG. 12 but illustrating the nozzle actuating turnbuckle devices in a maximum nozzle area position and illustrating in dot-and-dash lines a minimum area position of certain of said parts; and

FIG. 14 is a view taken along line 1414 of FIG. 5.

Referring first to FIGS. 13 'of the drawing reference numeral 10 designates the discharge end of the exhaust duct of an aircraft jet engine. A housing or engine nacelle 12 surrounds the duct 10, said housing forming part of the aircraft structure over which the surrounding air flows. An exhaust nozzle 14 is supported at the discharge end of the duct 10.

The nozzle 14 comprises a plurality of upstream nozzle segments 16 which are arranged in a circumferential assembly and each segment 16 is hingedly supported on the duct 10 at the upstream end of said segment as indi .cated at 18. The nozzle 14 also has a plurality of downstream nozzle segments arranged in a circumferential ice assembly, there being one downstream segment 20 for each upstream segment 16 with the upstream end of each downstream segment 20 being pivotally connected at 22 to the downstream end of its upstream segment 16. Thus the nozzle 14 may be considered to comprise a plurality of nozzle members 16, 20 arranged in a circumferential assembly with each nozzle member being hingedly supported at its upstream end as indicated at 18 and consisting of upstream and downstream segments 16 and 20 hingedly connected together at 22 to form a convergentdivergent nozzle.

A plurality of members 24 are disposed about the nozzle in circumferential assembly to form an annular shroud about the nozzle. As hereinafter described, the shroud members 24 are hingedly supported at their upstream ends for pivotal movement with the nozzle members 16 and 20 as illustrated in FIGS. 1-3.

Reference is now particularly made to FIGS. 3-14 which illustrate the detail construction of the nozzle members, shroud members and the actuating mechanism.

Each upstream nozzle member 16 comprises a longitudinally extending supporting beam 26 of hollow rectangular cross-section pivotally connected to the duct 10 at 18. A plurality of tandem-disposed hollow sheet metal sections or shoes 30 are secured along the inner side of each beam 26. The construction is such that each beam 26 with its shoes 30 forms a nozzle member 16 of T-shaped cross-section with the beam forming the leg of the T-shape and with each shoe forming the head of the T-shape. As seen in FIG. 10, the shoes of adjacent nozzle members 16 overlap each other circumferentially to form the inner surface of the nozzle with one set of alternate nozzle members having their shoes 30 disposed radially inwardly of and overlapping the adjacent set of alternate nozzle members.

Each of the shoes 30 has leg portions 32 which overlap the sides of and are detachably secured to its supporting beam, as by screws (not shown). With this construction should a portion of the inner nozzle surface be damaged this portion can readily be replaced simply by replacing the damaged shoes 30 with new shoes.

Each downstream nozzle member 20 has a construction similar to that of the upstream nozzle members 16. Thus each nozzle member 20 includes a longitudinallyextending supporting beam 34 which is pivotally connected at its upstream end, as indicated at 22 to its associated upstream beam 26. A plurality of tandem disposed shoes 36 are secured along the inner side of each beam 34 to form the inner surface of the nozzle. The general arrangement and shape of the shoes 36 and their attachment to their supporting beams 34 are similar to that of the upstream shoes 30. The width of the hollow interior of the supporting beams 34 progressively decreases in a downstream direction and becomes zero at the end of said members as shown in FIGS. 6-9.

It should be noted that the supporting beams 34 for the radially inward shoes 36 are relatively narrow in cir cumferential width as compared to the other beams 34 to permit a large overlap of the nozzle shoes 36 so that the nozzle members 20 will overlap throughout the desired range of nozzle area adjustment.

The duct 10 has an internal liner 37 to form a double wall construction providing an annular passage 38 through which a suitable cooling medium is supplied. In the case of a turbo-jet engine, for example, this cooling medium may be compressed air obtained from the engine compressor. Each upstream supporting beam 26 has a telescopic elbow connection 40, around its hinge 18, to the duct 10 to provide a passage for supplying said cooling air from said annular passage 38 into each supporting beam 26. Similarly, each downstream supporting beam 34 has a telescopic elbow connection 42, around its hinge 22, to the adjacent end of associated upstream beam 26 to provide a passage for supplying cooling medium from each upstream beam 26 to its respective downstream beam 34.

Openings 44 are provided in each beam 26 so that cooling medium can flow threefrom into each of its shoes 30. Similarly openings 46 are provided in each beam 34 for flow of the cooling medium from said beams 34 into each of these shoes 36 with the exception possibly of the most downstream shoe 36 on each beam 34- since these latter shoes may not need any internal cooling.

The downstream end of each shoe 30 and 36 overlaps slightly or projects radially inwardly slightly beyond the shoe downstream therefrom to provide a stepped construction at the juncture of said shoes. This stepped construction is also provided at the junction of the most downstream shoe 30 of each upstream supporting beam 26 with the most upstream shoe 36 on the associated downstream supporting beam 34. Each shoe 30 and 36 has a narrow slot or opening 48 extending across the stepped end of said shoe for flow of cooling medium therethrough over the inner surface of the adjacent downstream shoe. Except for the slots 48 the ends of the shoes 30 and 36 are closed. Also the inner shell 37 of the duct slightly overlaps the most upstream shoes 30 as indicated at 49 for flow of cooling medium over the inner surface of said latter shoes 30.

With this arrangement a film of cooling medium is provided over the inner nozzle surface of each of the shoes 30 and 36 to protect said surface from the hot exhaust gases discharging through the nozzle. Preferably the relative sizes of the passages and openings are such that most of the cooling air supplied to the hollow upstream beams 26 is supplied over the otherwise hotter upstream portion of the nozzle surface with the balance flowing into the downstream beams 34 for flow over the remaining downstream portion of the nozzle surface.

Reference is now made to FIGS. 4, 5, 12, 13 and 14 for details of the nozzle actuating mechanism. For actuating the nozzle segments 16 and 20 a pair of internal annular gears 50 and 52 are provided. These gears are disposed in an annular housing 54 which is supported from the duct 10 by links 56. A plurality of pinion gears 58 and 60 are journaled within the housing 54, said pinions 58 and 60 meshing with the internal gears 50 and 52 respectively. In this way the internal gears 50 and 52 are floatingly supported on the pinions 50 and 52. There is one pinion 58 for each upstream nozzle segment 16 and one pinion 60 for each downstream nozzle segment 20.

Each pinion 58 has a shaft 62 extending therefrom and having a universal coupling connection 64 with a shaft 66. The flexible coupling 64 and the flexible couplings hereinafter described are illustrated in FIGS. 4 and 14- but only diagrammatically in FIG. 14. Each shaft 66 extends into a gear box 68 and each gear box 68 has an extension 70 forming a housing for its shaft 66. The end of the shaft housing 70 remote from the gear box 68 has flanges 72 (FIG. 14) forming a forked end which is pivotally connected at 74 to the annular housing 54. Each shaft 66 terminates in a worm gear 76 which meshes With a worm wheel 78 in its gear box 63.

Similarly each pinion 60 has a shaft 80 extending therefrom and having a universal coupling connection 82 with a shaft 84 which connects with a second universal coupling 86 at a gear box 88 and a shaft 90 extends therefrom into said gear box. Each shaft 98 has a worm gear 92 at its end meshing with a worm wheel 94 in its gear box 88. Each gear box 88 has an extension 96 forming a housing for its shaft 84. The end of the housing extension 96 remote from the gear box 88 has side extensions 93 and 100 forming a forked end which is pivotally connected to the annular housing at 102. Thus there is a gear box 68 and housing extension 70 for each upstream nozzle segment 16 and there is a gear box 88 and housing extension 96 for each downstream nozzle segment. The forked end 98-100 of each housing extension 96 straddles the end of the housing extension 70 for its associated upstream nozzle segment, as seen in FIG. 14, to provide a wide connection for said extension 96 thereby providing the gear boxes 88 with a support which has substantial lateral rigidity.

The shaft connection to each gear box 88 has the second universal coupling 86 in order that the worm gear 92 of each gear box 88 preferably has its axis co-planar with the axis of the worm gear 76 of the associated gear box 68.

As hereinafter described each worm wheel 78 forms part of a turnbuckle-like device which devices are connected to form an annular structure 104 which is expandable and contractible by rotation of the worm wheels 78. The annular structure 104 is co-axially disposed about the upstream nozzle segments 16 and is connected thereto by links 106, one end of each link 106 being pivotally connected to an upstream nozzle segment and the other end is pivotally connected to the annular structure 104. Similarly each worm wheel 94 forms part of a turnbuckle-like device which devices are connected together to form annular structure 108 which is expandable and contractible by rotation of the worm wheels 94. Said annular structure 108 is co-axially disposed about the downstream nozzle segment 20 and is connected thereto by links 110 each pivotally connected at one end to a nozzle segment 20 and at its other end to the annular structure 108.

The annular structures 104 and 108 are similar so that it is only necessary to illustrate and describe the details of one. The details of the annular structure 108 are shown in FIGS. 12 and 13. As there illustrated, each worm wheel 94 is part of a threaded element 120 having threads of opposite hand at its ends. Each threaded element 120 is disposed between or intermediate end elements 122 and 124 which are screwed on the ends of the element 120. Thus each intermediate element 120 with its end elements 122 and 124 form a turnbucklelike device. The end elements 122 and 124 are slidably journaled in their gear boxes 88 and each slidably extends from its gear box 88 for pivotal connection to the end element extending from the adjacent side of the adjacent gear box 88 as indicated at 126 whereby the turnbuckle devices 120, 122, 124 are pivotally connected together in end-to-end relation to form the annular structure 108. The connection of the end elements 122 and 124 together prevents their rotation as the intermediate elements 120 are rotated. Hence rotation of each intermediate element 120 causes its associated end elements 122 and 124 to be screwed therealong toward or away from each other, depending on the direction of rotation,

. thereby shortening or lengthening the annular structure 108 to decrease or increase its diameter. In this way by rotating the intermediate elements of the turnbucklelike devices 120, 122, 124 in the same direction the annular structure 108 can be expanded or contracted depending on the direction of rotation.

As also shown in FIGS. 12 and 13 the links for each downstream nozzle segment 20 are pivotally connected at one end to a pin 130 secured to the beam 34 of said downstream segment 20 and at its other end is connected to the annular structure 108 by pivotally connecting to the gear box 88 for said downstream segment 20. At this point it should be noted that the gear boxes 88 move radially with its associated turnbuckle like devices, 120, 122, 124 upon expansion or contraction of the annular structure 108.

It is apparent now that rotation of the annular gear 52 in one direction is effective to rotate each of the worm wheels 94 in the same direction to expand or contract the annular structure 108, depending on the direction of rotation of the gear 52. Likewise it is apparent that expansion of the annular structure 108 is effective, through the links 110, to move the downstream nozzle segments 20 about their hinge connections 22 to increase the nozzle exit area. Similarly contraction of the annular structure 108 is effective to decrease the nozzle exit area.

A motor 132 (FIG. 4) is provided for rotatively positioning the annular gear 52 to set the nozzle exit area. For this purpose the motor 132 may be connected to one of the pinions 60 as illustrated or to its own pinion meshing with the gear 52.

The annular structure 104 is similar to the annular structure 108 described. Thus rotation of the ring gear 50 is effective to rotate each of the worm wheels 78 in the same direction to expand or contract the annular structure 104, depending on the direction of rotation of the gear 50. Expansion of the annular structure 104 is effective to move the upstream nozzle segments 16 about their pivotal connections 18 to increase the nozzle throat area and contraction of said annular structure is eifective to decrease said throat area. A motor 134 (FIG. 4) is provided for rotatively positioning the annular gear 50 to set the nozzle throat area.

The shroud members 24 are hingedly supported at their upstream ends to the annular housing 54 as indicated at 140. Each shroud member 24 is flexible and is connected to the nozzle structure at a plurality of points along said member. Thus the gear boxes 88 are pivotally connected by links 142 to the shroud members. Also each housing extension 96 has a lug 144 with a cam slot 146 which is engaged by a pin 148 secured to the associated shroud member 24. Each downstream nozzle member 20 also has a pair of lugs 150 and 152 with cam slots 154 and 156 respectively and engaged by pins 158 and 160 respectively, said pins being secured to the associated shroud member 24. With this structure each shroud member 24 is connected at a plurality of points spaced therealong to the associated downstream nozzle segments 20, either directly to said segment as in the case of the pins 158 and 160 or indirectly through the actuating mechanism for said downstream segments as in the case of the pins 148 and links 142.

The cam slots 146, 154 and 156 are designed so that the shroud elements 24 bend slightly (convex as viewed from outside the nozzle) in the minimum area positions of the nozzle as in FIG. 1. In the maximum area positions of the nozzle the shroud elements are further bent in order to accommodate the annular structure 108 between the shroud and nozzle and still make the exit area of the shroud as small as possible. Thus with the nozzle positions of FIGS. '2 and 3, particularly FIG. 3, the nozzle shroud has a barrel-like profile having a maximum diameter intermediate its ends. In all positions of the nozzle, its shroud members 24 form a smooth or streamlined rearward continuation of the engine housing or nacelle 12 and with the flexing of said shroud members 24 the area of the downstream end of the shroud is held to a minimum in all positions of nozzle adjustment so as to minimize drag.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modifications.

I claim as my invention:

1. A variable-area convergent-divergent nozzle and shroud combination comprising a plurality of nozzle members arranged in circumferential assembly, each pivotally supported at its upstream end and each comprising an upstream nozzle segment and a downstream nozzle segment pivotally connected to said upstream nozzle segment to form a convergent-divergent nozzle; a plurality of flexible members arranged in a circumferential assembly about said nozzle members to form an annular shroud about said nozzle with each shroud member being pivotally supported at its upstream end; nozzle adjusting means disposed between said nozzle members and shroud members and operatively connected to said nozzle members for pivotally moving said nozzle means to vary the nozzle area; and means connecting each shroud member to an adjacent nozzle member at a plurality of points along said shroud member, said connections including means such that when said nozzle members are in their maximum nozzle area position said shroud has a barrel-like shape with a maximum diameter intermediate its ends and said shroud members becoming more straight as they are moved toward their minimum area position.

2. A variable area exhaust nozzle for a jet engine; said nozzle comprising a plurality of nozzle members arranged in circumferential assembly, each pivotally supported at its upstream end and each comprising an up stream nozzle segment and a downstream nozzle segment pivotally connected to said upstream segment; a first annular structure co-axially disposed about said upstream segments for pivotally adjusting said upstream segments; said first annular structure comprising a plurality of turnbuckle devices, there being one turnbuckle device for each upstream nozzle segment; each turnbuckle device having a pair of end elements and an intermediate element connected to its said end elements so that rotative adjustment of the intermediate element of said turnbuckle device relative to its end elements is effective to vary the length of said turnbuckle device, said turnbuckle devices being disposed in end-to-end relation with the end elements of adjacent devices being pivotally connected together; means for simultaneously adjusting each of said turnbuckle devices so as to adjust the diameter of said first annular structure; means connecting each of said upstream segments to said first annular structure for adjustment of the nozzle throat area in response to adjustment of the diameter of said annular structure; a second annular structure co-axially disposed about said downstream segments, said second annular structure being similar to said first annular structure but being connected to said downstream segments for adjustment of the nozzle exit area, said means for adjusting said turnbuckle devices comprising a plurality of shafts extending upstream from said turnbuckle devices and a plurality of pairs of meshing gears, there being one shaft and one pair of meshing gears for each of said turnbuckle devices with one of said gears being connected to said shaft and with the other of said gears being connected to the intermediate element of its associated turnbuckle device; and a housing structure for each of said shafts and pair of gears with each housing structure being pivotally supported at its upstream end, the pivotally supported end of the housing structure for the adjusting means of a downstream nozzle segment having a forked construction which straddles the pivoted end of the housing structure for the adjusting means of the upstream nozzle segment connected to said downstream nozzle segment.

References Cited in the file of this patent UNITED STATES PATENTS 2,669,834 Helms Feb. 23, 1954 2,697,907 Gaubatz Dec. 28, 1954 2,699,648 Berkey Jan. 18, 1955 2,780,056 Colley Feb. 5, 1957 2,822,199 Johnson Feb. 4, 1958 2,831,319 Geary Apr. 22, 1958 2,870,600 Brown Jan. 27, 1959 2,926,489 Halford Mar. 1, 1960 

